It is well known to provide a support assembly for the mounting or suspension of the operating components of clothes washing machines, which assembly moves in a nodal fashion in damping out undesirable movement of the operating components of the machine. A number of such mounts or suspensions have been or currently are in production by various manufacturers of upright washers. The support assembly has two, somewhat conflicting, objectives. A general object of such assemblies is to minimize the unbalance forces exerted on the cabinet at the pivotal or nodal point of movement. Such unbalance forces tend to cause vibration of the floor and movement or walking of the washing machine.
The second object is to control excursion of the working components of the machine, particularly the clothes basket or receptacle, during the spin operation. Such excursions may become particularly large as the clothes receptacle passes through what is called the "critical" speed. In order to centrifugally extract the maximum amount of water from the fabrics which have been washed or rinsed, the basket is rotated at very high speed. In the critical speed range of the basket, the excursion of the basket caused by unbalanced loads tends to become regenerative and the basket tries to move far off its central axis. This can cause the basket to strike other components of the machine and cause objectionable noise or damage the machine. The support assembly applies a frictional force opposing such large excursions, particularly as the receptacle approaches through its critical speed range. Thus it can be seen that the object of isolating unbalance forces from the cabinet is enhanced by reducing as much as possible the frictional forces present in the support assembly during small excursions while damping unwanted large excursions is enhanced by increasing the frictional forces opposing the excursion.
When the clothes receptacle is spun or rotated at high speed to centrifugally extract water from fabrics, the moving system tends to move about a point in space which can be termed its natural node of operation. Often with currently produced machines this natural node is at a point below the surface on which the machine is sitting. In damping the movement of the system during spin, particularly during the critical speed range, frictional forces are applied to the system. It is advantageous that these frictional forces during critical speed be made as large as practical if the unbalanced load will cause large excursions. At the same time it is of benefit in reducing the forces transmitted to the support surface and thus the resulting tendency of the machine to vibrate or walk if such frictional forces are applied so that they pass through the natural node of movement of the machine.
When the basket has passed through the critical speed range and is approaching terminal speed, the moving system tends to center itself and not vibrate or oscillate far off of the vertical axis of the machine. It is advantageous to provide a low friction support arrangement for the machine which allows it to move in the small arcs or excursions with minimum frictional forces in the system, as the higher the degree of friction the greater the vibrational forces transferred to a cabinet and support surface. Also some machines, such as orbiting or wobble machines for example, have a natural node of operation during agitation operations, that is when the fabrics are being agitated in liquid to wash or rinse them. This second or agitation node of operation often is different than the natural node of operation during the centrifugal extraction step or phase. It is advantageous to provide a mount for the working components of a machine which has minimal frictional resistance to movement of the basket during the terminal speed spin and during agitation operations with minimum friction. The reduction of the frictional forces or torque can be enhanced both by using low coefficient of friction interface and by making the relatively movable surfaces as close to the vertical axis of the machine as possible in order to minimize the radius. In the machines which have a second natural node of operation during their agitation operation it is advantageous to have the low friction node of the support assembly approximate the natural agitation node of the machine.
Copending application of Richard A. Waugh, 9D-HL-14796, and assigned to General Electric Company, assignee of the present invention, is incorporated herein by reference. That application illustrates and describes a suspension assembly which provides relatively low frictional force resistance to low amplitude movement of the machine mount and relatively large frictional force resistance to large amplitude movement of the mount. However the entire suspension assembly is constructed such that all the relative movement is about a single node, preferably the natural node of operation during centrifugal extraction.